1. Field of the Invention
The invention relates to an apparatus for adjusting the height of the upper fixing or guide fitting for the shoulder belt of a safety belt system, particularly in motor vehicles. The apparatus includes a guide rail mounted on part of the vehicle body, having a guide slot and recesses in which at least one associated locking member engages. This locking member is mounted on a sliding member which carries the fixing or guide fitting and is capable of being locked into or released from the recesses by means of a handle.
2. Description of the Prior Art
German Offenlegungsschrift No. 26 25 572 (Daimler-Benz) discloses a vertically adjustable fitting of the kind described above wherein the locking of the sliding member carrying the fitting in the guide rail is effected by locking cams located on the sliding member engaging in recesses provided on both sides of the guide slot. The sliding member with its locking cams is pressed towards the upper part of the guide rail and into the associated recesses by spring force acting at right angles to the guide rail. The fitting is adjusted by manual pressure on a fixing screw provided on the sliding member or on a cover held by this screw, which serves as a handle. Under the effect of the pressure applied by the hand, the sliding member moves into the guide rail, counter to the spring force, until the locking cams are disengaged from the recesses in the perpendicular direction. In this pressed-in state, the sliding member with fitting is then vertically adjustable in the guide rail.
The apparatus as disclosed in German Offenlegungsschrift No. 26 25 572 (Daimler-Benz) has the advantage that the locking mechanism can become disengaged when the vehicle is subjected to strong lateral impact, since relatively heavy parts such as the fitting with the fixing screw and sliding member are supported only against the action of a simple helical spring.
German Offenlegungsschrift No. 26 55 995 (Porsche) also discloses a vertically adjustable guide fitting for a safety belt wherein disengagement is effected by moving the sliding member into the interior of the guide rail, said disengagement being achieved by turning a screw in this case. The screw simultaneously serves as a movable fastening for the guide fitting, with the consequent disadvantage being that the sliding member in the guide rail may become detached under certain unfavorable circumstances.
German Offenlegungsschrift No. 23 03 222 (Opel) also discloses an apparatus with features of the kind described hereinbefore, wherein the sliding member is adjusted by pressing with the hand against the force of a spring onto the head of a screw and subsequently moving the sliding member in the perpendicular direction. This apparatus also is not absolutely safe if the vehicle is subjected to a violent lateral impact.
Moreover, German Offenlegungsschrift No. 26 03 979 (Hakanssons) describes a vertically adjustable fitting with a guide rail and sliding member, wherein a small hand wheel is provided on the sliding member and the rotation of this wheel spreads open two bolts. These bolts then jam inside the guide rail fixing the sliding member in position. Thus, the sliding member is held here in its prescribed vertical position by friction alone, which may be very unsafe if there is any wear on the bolts.
German Offenlegungsschrift No. 24 12 253 (Schlegelmilch) also discloses a guide rail wherein a sliding member is clamped by a jamming action and a small handwheel is provided on a screw to operate therewith. At the same time, this specification discloses the arrangement of a threaded spindle in a guide rail wherein the associated sliding member can be moved up and down by rotating the spindle by means of a handwheel.
The vertical adjustment devices as disclosed in the prior art as a whole, do not give sufficient consideration to the important aspect of comfort when the safety belts are fastened by the driver and passengers. The comfort of wearing the belt has a critical influence on the wearing rate and hence on the safety of the person in the vehicle, more particularly a motor vehicle. In other words the more comfortable the belt is to fasten, the more likely it is to be worn.
As shown in the prior art, vertical adjustment of the fitting is difficult and uncomfortable for the user to carry out. In fact, the fitting can really be adjusted only after the person has climbed in and correctly positioned the vehicle seat. The adjustment apparatus then is generally behind the user and above his shoulder. In this position, the simultaneous sequence of movements required to disengage and adjust the fitting, with the directional movements required with known apparatus, are very uncomfortable for the user to carry out, particularly as the freedom of movement of the user is restricted by the belt which is already fitted over the body.